Investment in West Texas LPG Pipeline L.P. - Selected Financial Information for Equity Method Investees (Details) - West Texas LPG Pipeline L.P. - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	7 Months Ended	9 Months Ended
	Jul. 31, 2018	Sep. 30, 2017	Jul. 31, 2018	Sep. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Total Assets	$ 928,349		$ 928,349		$ 837,163
Long-Term Debt	0		0		0
Members' Equity	868,894		868,894		$ 787,426
Revenues	9,104	$ 22,009	55,534	$ 63,148
Net Income	$ 3,283	$ 3,945	$ 16,642	$ 12,734